What Does PD Mean?
PD stands for the pupillary distance, and it refers to the distance in millimeters between the center of one pupil to the center of the other.
Why it is so Important？
Wrong PD may result in viewing through a spot on the lens other than the ‘optical center’. You may experience blurriness, eye strain, double vision, headaches etc.
How to Measure Your PD?
Prepare a Mirror and a Ruler
Stand 8-10 inches away from the mirror,and look into the mirror
Pick a ruler and place it just above the eyes and lining up the 0 of the ruler with the center of the pupil of your right eye.
With the zero now centered with you right eye,close your right eye and open your left eye to see where the center of your left pupil aligns on the ruler.
Measure the distance between the 0 and the mark you made.This would be your PD.For accuracy,repeat the steps for 3-4 times.
EYEKEEPER READING GLASSES OPTICAL PERFORMANCE
The pupil distance(PD) is 59-63mm, the deviation for pupil distance(PD) less than 2mm, the deviation for strength less than 0.02, the deviation for lenses's horizontal line less than 1mm.